81538723 has 8 divisors (see below), whose sum is σ = 93899520. Its totient is φ = 69356040.

The previous prime is 81538693. The next prime is 81538739. The reversal of 81538723 is 32783518.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81538723 - 2⁹ = 81538211 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81538753) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 43543 + ... + 45376.

It is an arithmetic number, because the mean of its divisors is an integer number (11737440).

Almost surely, 2^81538723 is an apocalyptic number.

81538723 is a deficient number, since it is larger than the sum of its proper divisors (12360797).

81538723 is a wasteful number, since it uses less digits than its factorization.

81538723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89057.

The product of its digits is 40320, while the sum is 37.

The square root of 81538723 is about 9029.8794565598. The cubic root of 81538723 is about 433.6319782876.

The spelling of 81538723 in words is "eighty-one million, five hundred thirty-eight thousand, seven hundred twenty-three".